Expandable introducer sheath

ABSTRACT

An expandable introducer sheath provided with a steering mechanism is disclosed. The introducer sheath is configured for providing a prosthesis delivery system percutaneous access to a patient&#39;s vasculature. The introducer sheath includes a sheath component defining a central lumen and having a longitudinally-extending, radially-expandable portion. The sheath component also includes a steering wire slidably disposed within a wall thereof that longitudinally extends along the radially-expandable portion. When the steering wire is in a slackened configuration, the steering wire permits a width of the radially-expandable portion to increase. When the steering wire is in a taut configuration, the steering wire permits a distal portion of the sheath component to be manipulated or bent in order to align a distal port of the introducer sheath, for instance, with an ostium of a branch vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of prior U.S. application Ser.No. 15/466,098, filed Mar. 22, 2017, now U.S. Pat. No. [to be assigned],which claims the benefit of prior U.S. Appl. No. 62/315,782, filed Mar.31, 2016, which are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to an introducer sheath for providing atranscatheter valve prosthesis delivery system percutaneous access to apatient's vasculature, and, more particularly to an introducer sheathhaving an expandable section for accommodating passage of thetranscatheter valve prosthesis delivery system therethrough.

BACKGROUND OF THE INVENTION

An introducer sheath provides percutaneous access to the vascular systemof a patient and functions to permit the introduction and positioning ofvarious minimally invasive medical devices within the patient'svasculature. Minimally invasive medical devices refer to inter alia anytype of catheter sized to be introduced into the vasculature to includetranscatheter valve prosthesis delivery systems. A conventionalintroducer sheath includes an elongate tubular component that defines alumen of the introducer sheath, a hub component, and a hemostasis valve.It is known to commence a minimally invasive procedure within thevasculature by initially forming a percutaneous entry point via theSeldinger technique into a suitable vessel of the patient, such as afemoral, brachial, or radial artery. Thereafter, the elongate tubularcomponent of the introducer sheath is partially inserted into thevasculature at the percutaneous entry point with a proximal port of theintroducer sheath hub being accessible by a clinician so that minimallyinvasive medical devices may be introduced into and advanced through thelumen of the introducer sheath. In many minimally invasive procedureswithin the vasculature, a guidewire may first be inserted through theintroducer sheath and subsequently advanced through the vasculature (andin certain applications another body structure) to a treatment site.

Recently minimally invasive approaches have been developed to facilitatecatheter-based implantation of a valve prosthesis on a beating heartthat are intended to obviate the need for the use of classicalsternotomy and cardiopulmonary bypass. More particularly, flexibleprosthetic valves supported by stent structures that can be deliveredpercutaneously using a catheter-based delivery system have beendeveloped for heart valve replacement, and may be referred to herein asa transcatheter valve or a transcatheter heart valve prosthesis.Transcatheter heart valve prostheses may include either self-expandingor balloon-expandable stent structures with valve leaflets attached tothe interior of the stent structure. They are configured to be reducedin diameter, by crimping onto a balloon catheter or by being containedwithin a sheath or outer tubular component of a delivery catheter, andthereafter advanced through the venous or arterial vasculature. Once thetranscatheter heart valve prosthesis is positioned at the treatmentsite, for instance within an incompetent native valve or a previouslyimplanted prosthetic heart valve, the frame or stent structure may beexpanded to hold the prosthetic heart valve firmly in place.

The actual shape or configuration of any particular transcatheter heartvalve prosthesis to be delivered in a transcatheter implantationprocedure is dependent, at least to some extent, upon the native heartvalve being replaced or repaired, i.e., mitral valve, tricuspid valve,aortic valve, or pulmonary valve. Most transcatheter heart valveprosthesis will have a relatively large delivery profile, as will atleast a distal portion of a catheter-based delivery system within whichthe prosthesis is held in a compressed configuration. The use of suchlarger delivery profile catheter-based delivery systems, heretofore,required a larger diameter or sized introducer sheath in order toprovide suitable clearance within the lumen thereof to allow thecatheter-based delivery system to pass through the patient'svasculature. However, larger diameter or sized introducer sheaths may besuitable for use only in patients with sufficient vessel size toaccommodate such an introducer sheath. In order to extend theavailability of larger delivery profile transcatheter heart valveprostheses and their delivery systems to patients with smaller vesselsizes, expandable introducer sheaths with smaller diameters or sizesthat are configured to locally expand within the patient's vasculatureto allow passage of such prostheses and delivery systems are describedin U.S. Patent Application Pub. No. 2014/0121629 to Macaulay et al. andU.S. Patent Application Pub. No. 2014/0236122 to Anderson et al., eachof which is incorporated herein by reference in its entirety. Localizedradial expansion and subsequent recoil of segments of the expandableintroducer sheaths described in the Macaulay and Anderson publicationsmay be less traumatic on the patient's vessel than sustainedlongitudinal and radial expansion of a fixed, larger diameter introducersheath.

An expandable introducer sheath must be navigable through thevasculature, and, for certain procedures, it may be necessary for theclinician to accurately steer or deflect the introducer sheath so that adistal port or opening thereof may be aligned with an ostium of a branchor side vessel. It is known to employ a pull wire connected to a distalportion of certain catheters and controlled by a proximal handlecomponent. With such mechanisms, when a wire is pulled, the catheter isdeflected in the direction of the pulled wire. However, known pull wiremechanisms are insufficient and inadequate when it comes to accuratelyand controllably deflecting an expandable introducer sheath due to thelongitudinally-extending radially-expandable sections of such introducersheaths lacking sufficient stiffness or columnar strength to react in areliable and/or uniform fashion in response thereto.

In light of the above, a need exists for an expandable introducer sheathhaving a steering mechanism that provides accurate, safe, andpredictable deflection of the introducer sheath as it navigates theanatomy of the vasculature.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect hereof, an introducer sheath for providinga prosthesis delivery system percutaneous access to a patient'svasculature is disclosed. The sheath includes a sheath component havinga central lumen defined by a wall structure thereof, the wall structurebeing formed from a circumferentially continuous inner layer with aradially-expandable portion, and a circumferentially discontinuous outerlayer that is connected to the circumferentially continuous inner layer,the circumferentially discontinuous outer layer including first andsecond longitudinally-extending edges between which theradially-expandable portion of the inner layer is defined. Theradially-expandable portion of the circumferentially continuous innerlayer of the wall structure is disposed inwardly of the first and secondlongitudinally-extending edges of the circumferentially discontinuousouter layer of the wall structure in each of an unexpanded state and anexpanded state of the sheath component.

In accordance with another aspect hereof, an introducer sheath forproviding a prosthesis delivery system percutaneous access to apatient's vasculature is disclosed. The sheath includes a sheathcomponent having a wall structure formed from an inner liner with aradially-expandable portion, the radially-expandable portion having afirst width when the sheath component is in an unexpanded state and asecond width, greater than the first width, when the sheath component isin an expanded state, and an outer jacket that is connected to the innerliner, the outer jacket including first and secondlongitudinally-extending edges between which the radially-expandableportion of the inner liner extends. The radially-expandable portion ofthe inner liner of the wall structure is disposed inwardly of the firstand second longitudinally-extending edges of the outer jacket of thewall structure in each of the unexpanded state and the expanded state ofthe sheath component.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following description of embodiments thereof asillustrated in the accompanying drawings. The accompanying drawings,which are incorporated herein and form a part of the specification,further serve to explain the principles of the invention and to enable aperson skilled in the pertinent art to make and use the invention. Thedrawings are not to scale.

FIG. 1 depicts a side view of an introducer apparatus in accordance withan embodiment hereof.

FIG. 2 depicts a side view of an introducer sheath in accordance with anembodiment hereof.

FIGS. 2A and 2AA are cross-sectional views of a sheath component of theintroducer sheath of FIG. 2 taken at line A-A thereof, with FIG. 2Ashowing the sheath component in an unexpanded state and with FIG. 2AAshowing the sheath component in an expanded state.

FIG. 2B is a perspective view of an area B of the introducer sheathshown in FIG. 2 in accordance with an embodiment hereof with a wirestructure of the sheath component exposed for illustrative purposesonly.

FIG. 2BB is a perspective view of an area B of the introducer sheathshown in FIG. 2 in accordance with another embodiment hereof with a wirestructure of the sheath component exposed for illustrative purposesonly.

FIG. 2C depicts a cut away view of a handle component in accordance withan embodiment hereof.

FIG. 2D depicts a partial sectional view of an area D of the introducersheath shown in FIG. 2 .

FIG. 3 depicts an exemplary distal portion of a valve prosthesisdelivery system for use with an introducer sheath in accordanceherewith.

FIG. 4 depicts the distal portion of the valve prosthesis deliverysystem of FIG. 3 positioned within the segment B of the introducersheath of FIG. 2 .

FIG. 5 depicts a side view of an introducer apparatus 100 in accordancewith an embodiment hereof after being steered into a deflected statewith the distal portion of the valve prosthesis delivery system of FIG.3 distally extending therefrom.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. The terms “distal” and“proximal” are used in the following description with respect to aposition or direction relative to the treating clinician. “Distal” or“distally” are a position distant from or in a direction away from theclinician. “Proximal” and “proximally” are a position near or in adirection toward the clinician. The following detailed description ismerely exemplary in nature and is not intended to limit the invention orthe application and uses of the invention. Although the description ofthe invention is in the context of treatment of heart valves, theinvention may also be used where it is deemed useful in endoscopicprocedures, procedures in the coronary vessels, or procedures in theperipheral vessels. Furthermore, there is no intention to be bound byany expressed or implied theory presented in the preceding technicalfield, background, brief summary or the following detailed description.

An introducer apparatus 100 in accordance with an embodiment hereof isshown in FIG. 1 . Introducer apparatus 100 includes an introducer sheath110 and a dilator 120. Introducer sheath 110 has a sheath component 102and a handle component 104 attached at a proximal end 106 of the sheathcomponent 102. With reference to FIGS. 2 and 2A, the sheath component102 is a tubular structure that defines a central or interior lumen 209from the proximal end 106 to a distal end 108 thereof, wherein thedistal end 108 defines a distal port or opening 115 of the introducersheath 110. The handle component 104 includes a hemostasis valve (notshown), a proximal port 101, and a side port 103. By way of example, butnot limitation, in FIG. 1 a flush tube 105 having a Luer connector 107is shown coupled to the side port 103 of the handle component 104. Thedilator 120 is configured to slide through the introducer sheath 110,and more particularly is configured to be slidably disposed within thecentral lumen 209 of the sheath component 102 such that a distal portion122 of the dilator 120 distally extends from the distal port 115 of theintroducer sheath 110.

In order to track one or more minimally invasive medical device to atreatment site within a patient, such as to track a valve prosthesisdelivery system to an incompetent heart valve of a patient, a clinicianmust first establish percutaneous access to a patient's vasculature. Ina method of providing percutaneous access to a patient's vasculature inaccordance herewith, which is presented by way of example, but notlimitation, a puncture needle (not shown) may be inserted through theskin and into a vessel, such as one of a femoral, brachial, or radialartery. The puncture needle may then be slightly withdrawn until a flashof blood appears and thereafter a guidewire (not shown) may be insertedthrough the puncture needle and advanced into the vessel. With theguidewire in place, the introducer apparatus 100 may be advanced overthe puncture needle such that the dilator 120 enlarges the access pointinto the vessel and the sheath component 102 of the introducer sheath110 gains access to the vessel. Thereafter, the dilator 120 is removed,and the sheath component 102 of the introducer sheath 110 is left behindin the vessel holding the tract open and protecting the vessel fromtrauma as one or more minimally invasive medical devices aresubsequently introduced into the vessel therethrough.

The introducer sheath 110 in accordance with embodiments hereof isdescribed in more detail herein with reference to FIGS. 2, 2A, 2AA, 2B,2BB 2C, 2D, 4 and 5. FIG. 2 is a side view of the introducer sheath 110with the dilator 120 removed. Each of FIGS. 2A and 2AA is across-sectional view of the sheath component 102 of the introducersheath 110 taken at line A-A in FIG. 2 , with FIG. 2A showing the sheathcomponent 102 in an unexpanded state and with FIG. 2AA showing thesheath component 102 in an expanded state. FIG. 2B is a perspective viewof a segment B of the sheath component 102 shown in FIG. 2 with a wirestructure 212 in accordance with an embodiment hereof exposed forillustrative purposes only. FIG. 2BB is a perspective view of an area Bof the introducer sheath shown in FIG. 2 in accordance with anotherembodiment hereof with a wire structure 212B of a sheath componentexposed for illustrative purposes only.

Referring to FIGS. 2A, 2AA and 2B, the sheath component 102 includes awire structure 212, an inner liner 214, and an outer jacket 216 that arejoined to each other to form a tubular wall of the sheath component. Theinner liner 214 forms a circumferentially continuous inner layer 102 aof the sheath component 102, whereas together the outer jacket 216 andthe wire structure 212 may be considered to form a circumferentiallydiscontinuous outer layer 102 b of the sheath component 102, with thewire structure 212 providing kink resistance and reinforcement of thesheath component 102. In embodiments hereof, the inner layer 102 a ofthe sheath component 102 (formed by the inner liner 214) defines alongitudinally-extending, radially-expandable portion 218 between firstand second longitudinally-extending edges 211, 213 of the outer layer102 b of the sheath component 102 (formed by the outer jacket 216 andthe wire structure 212). In embodiments hereof, a sheath component maybe described as having a longitudinally-extending, radially-expandableportion, such as expandable portion 218, disposed between a reinforcedportion, such as a remainder of the sheath component 102 formed from atleast the circumferentially discontinuous outer layer 102 b of the outerjacket 216 and the wire structure 212.

In embodiments hereof, an inner liner may be formed fromtetrafluoroethylene (TFE), Teflon®, polytetrafluoroethylene (PTFE),polyethylene, polyethylene terephthalate (PET), or polyester. In anembodiment hereof, an inner liner may have a low coefficient of frictionon its inner surface to facilitate advancement of one or more minimallyinvasive medical devices through an introducer sheath in accordance withembodiments hereof. In embodiments hereof, an outer jacket may be formedfrom a polyurethane (e.g. Pellethane®, Elasthane™, Texin®, orTecothane®) and can include 20% barium sulfate added as a radiopacifier.In other embodiments, an outer jacket may be formed from a polyamidepolyether block copolymer, such as Pebax®, nylon 12, or polyethylene. Inother embodiments, an outer jacket may be loaded with tungsten orbismuth subcarbonate to add radiopacity so that an introducer sheath inaccordance with embodiments hereof may be radio detectable (radiopaque).

In embodiments hereof, a wire structure may be formed of a shape memorymaterial such as a nickel titanium alloy (nitinol), with a diameter ofthe wire ranging, for e.g., from approximately 0.005 inches toapproximately 0.02 inches. In other embodiments, a wire structure may beformed of a resilient material, such as anickel-cobalt-chromium-molybdenum alloy (MP35N), stainless steel, highspring temper steel, or any other metal or composite having elasticproperties to permit radial expansion and recoil of an introducer sheathin accordance with embodiments hereof.

In an embodiment hereof, the wire structure 212 of the outer layer 102 bof the sheath component 102 is formed from a shape memory or resilientmaterial to actively recoil or return the radially-expandable portion218 of the sheath component 102 to its original, unexpanded state (asrepresented by the cross-section shown in FIG. 2A) after passagetherethrough of a valve prosthesis delivery system. In order toillustrate this functionality, FIG. 3 depicts an exemplary distalportion of a valve prosthesis delivery system 350 that includes a distalsegment or capsule 352 within which a transcatheter heart valveprosthesis (not shown) may be held in a compressed deliveryconfiguration, and FIG. 4 depicts the distal segment 352 being distallyadvanced within the segment B of the introducer sheath 110. Due to therelatively larger delivery profile of a compressed heart valveprosthesis, the distal segment 352 of the valve prosthesis deliverysystem 350 has a delivery profile (or outer diameter) that is wider orlarger than a delivery profile (or outer diameter) of a remainingproximal segment 354 of the valve prosthesis delivery system 350. Inaccordance with embodiments hereof, the introducer sheath 110 isconfigured to radially expand as the distal segment 352 of the valveprosthesis delivery system 350 is distally advanced or pushedtherethrough, wherein the dashed arrows in FIG. 4 are intended torepresent the distal movement D_(M) of the valve prosthesis deliverysystem 350 relative to the introducer sheath 110.

More particularly with reference to FIGS. 2A, 2AA, 3 and 4 , theradially-expandable portion 218 of the sheath component 102 of theintroducer sheath 110 is configured to locally and temporarily expand orstretch from a width W₁ to a width W₂ to transition or expand an area orsegment 402B of the sheath component 102 within which the distal segment352 of the valve prosthesis delivery system 350 is positioned as it isdistally advanced relative to the introducer sheath 110. When theradially-expandable portion 218 of the sheath component 102 is at thewidth W₁, the central lumen 209 of the sheath component 102 has areduced, first inner diameter D₁ in all unexpanded areas or segments402A, 402C (see FIGS. 2A and 4 ). When the radially-expandable portion218 of the sheath component 102 is transitioned to the width W₂ due tothe distal segment 352 being disposed therein, the central lumen 209 ofthe sheath component 102 has an expanded, second diameter D₂ in theexpanded area or segment 402B (see FIGS. 2AA and 4 ). It should beevident from this description that the expanded area or segment 402Bchanges longitudinal position along the sheath component 102 tocorrespond with the continued distal advancement of the distal segment352 through (and relative to) the introducer sheath 110, such that thepositions of segments 402A, 402B, 402C shown in FIG. 4 are intended tobe illustrative and not limiting in any way.

By way of example and not limitation heart valve prosthesis deliverysystems suitable for use with an introducer sheath in accordance withembodiments hereof are described in further detail in U.S. Pat. Appl.Pub. No. 2014/0364939 to Deshmukh et al., U.S. Pat. No. 8,562,673 toYeung et al., U.S. Pat. No. 8,579,963 to Tabor, U.S. Pat. No. 8,974,524to Yeung et al., U.S. Pat. No. 8,998,980 to Shipley et al., and U.S.Pat. No. 9,149,358 to Tabor et al., each of which is incorporated byreference herein in its entirety.

With reference to FIGS. 2A and 2B, the wire structure 212 curves orbends around a longitudinal axis L_(A) of the sheath component 102 intoa C-shaped configuration with first and second series of curved portions221, 223 of the wire structure 212 aligning with respective first andsecond longitudinally-extending edges 211, 213 of the outer layer 102 bof the sheath component 102. In an embodiment hereof by way ofillustration and not limitation, each of a series of curved portion 221,223 has a respective eyelet 225, 227 formed on or secured thereto suchthat the wire structure 212 may also be considered to define or includefirst and second series of eyelets 225, 227 that align with respectivefirst and second longitudinally-extending edges 211, 213 of the outerlayer 102 b. In other embodiments, every other or every third curvedportion 221, 223 may have a respective eyelet 225, 227 formed thereonwithout departing from the scope hereof. In still other embodiments,only one or more consecutive or non-consecutive curved portions 221, 223located along a distalmost portion of the sheath component 102 may havea respective eyelet 225, 227 formed thereon without departing from thescope hereof. When the inner and outer layers 102 a, 102 b are bonded toeach other during formation of the sheath component 102, at least thefirst and second series of eyelets 225, 227 of the wire structure 212are disposed within respective longitudinally-extending channels orpockets 228 a, 228 b formed within the outer layer 102 b. Thelongitudinally-extending channels 228 a, 228 b extend within the outerlayer 102 b substantially in parallel with respective first and secondlongitudinally-extending edges 211, 213 of the outer layer 102 b, aswell as substantially in parallel with respective first and secondlongitudinally-extending sides 231, 233 of the radially-expandableportion 218. The first and second sides 231, 233 may be also bedescribed herein as opposing sides 231, 233 of the radially-expandableportion 218.

In another embodiment with reference to FIGS. 2A and 2BB, first andsecond series of curved portions 221B, 223B of the wire structure 212Baligning with respective first and second longitudinally-extending edges211, 213 of the outer layer 102 b of the sheath component 102 do notinclude eyelets. In such an embodiment when the inner and outer layers102 a, 102 b are bonded to each other during formation of the sheathcomponent 102, at least the first and second series of curved portions221B, 223B of the wire structure 212B are disposed within respectivelongitudinally-extending channels 228 a, 228 b formed within the outerlayer 102 b.

With reference to one or more of the prior described figures, a steeringmechanism that provides accurate, safe, and predictable deflection ofthe sheath component 102 of the introducer sheath 110 will now bedescribed. The steering mechanism includes a steering wire 240 that isoperably coupled to a rotatable knob 242 of the handle component 104.Broadly described, the steering wire 240 extends from the handlecomponent 104 to the distal end 108 of the sheath component 102 and isslidably disposed therebetween within the longitudinally-extendingchannels 228 a, 228 b formed within the outer layer 102 b of the sheathcomponent 102. The steering wire 240 may be described as having a firstsegment 240 a slidably disposed within the longitudinally-extendingchannel 228 a of the outer layer 102 b, and longitudinally extendingessentially in parallel with the first side 231 of the expandableportion 218 between the distal end 108 of the sheath component 102 andthe handle component 104. Similarly, the steering wire 240 may bedescribed as having a second segment 240 b slidably disposed within thelongitudinally-extending channel 228 b of the outer layer 102 b, andlongitudinally extending essentially in parallel with the second side233 of the expandable portion 218 between the distal end 108 of thesheath component 102 and the handle component 104. In embodiments inaccordance herewith, the steering wire 240 may also include a lateralsegment 240 c defined or extending between respective distal ends of thefirst and second segments 240 a, 240 b, wherein at least a portion ofthe lateral segment 240 c is slidably disposed within the expandableportion 218 of the sheath component 102 proximal of a distal end 119 ofthe expandable portion 218. As used herein with reference to the firstand second segments 240 a, 240 b of the steering wire 240 “slidably”denotes back and forth movement in a longitudinal direction along thelongitudinal axis L_(A) of the introducer sheath 110, and as used hereinwith reference to the lateral segment 240 c of the steering wire 240“slidably” denotes back and forth movement in a substantially transversedirection relative to the longitudinal axis L_(A) of the introducersheath 110.

FIG. 2D depicts a partial sectional view of an area D in FIG. 2 of thesheath component 102 with a distalmost portion of the channel 228 b laidopen for illustrative purposes. In embodiments in accordance herewith,the second segment 240 b of the steering wire 240 may slidably extend orpass through one or more of the second series of eyelets 227 (or one ormore of the second series of curved portions 223) that lie within thechannel 228 b particularly along the distalmost portion of the sheathcomponent 102, as shown in FIG. 2D. Similarly although not shown indetail, the first segment 240 a of the steering wire 240 may slidablyextend or pass through one or more of the first series of eyelets 225(or one or more of the first series of curved portions 221) that liewithin the channel 228 a, particularly along a distalmost portion of thesheath component 102. In accordance with embodiments hereof, at leastthe distalmost portions of the first and second segments 240 a, 240 b ofthe steering wire 240 include one or more stops, bumps or protrusions246 that are disposed distal of a corresponding eyelet 225, 227 (orcurved portion 221, 223). The stops 246 are sized to be larger than anopening of the corresponding eyelet 225, 227 (or curved portion 221,223), as shown in FIG. 2D for the distalmost portion of the secondsegment 240 b.

The spatial relationship between the stops 246 and eyelets 225, 227 (orcurved portions 221/223) is provided to permit limited distal movementof the first and second segments 240 a, 240 b of the steering wire 240relative to the eyelets 225, 227 (or curved portion 221, 223) in adistal direction to thereby allow expansion of the expandable portion218. Stated more particularly with reference to FIG. 2D, stops 246 a,246 b are each disposed between a respective proximal and distal eyelet227 and each stop 246 a, 246 b may be distally advanced up to a distanceMD by the sliding movement of the second segment 240 b of the steeringwire 240 before the second segment 240 b of the steering wire 240 isprevented from further distal movement by contact being made by thestops 246 a, 246 b with its respective distal eyelet 227.

In addition, when the stops 246 engage with their corresponding proximaleyelets 225, 227 (or curved portions 221/223) as the first and secondsegments 240 a, 240 b of the steering wire 240 are proximally pulled ortensioned the interaction between the stops and distal sides or ends ofthe eyelets/curved portions functions to return or maintain theexpandable portion 218 in an unexpanded state, such as during trackingof the sheath component within the vasculature. With continuedtensioning of the first and second segments 240 a, 240 b of the steeringwire 240 in a proximal direction, a distal portion 502 of the sheathcomponent 102 may be bent or deflected into the deflected or curvedstate shown in FIG. 5 by a corresponding bending force being applied bythe stops 246 against the distal sides or ends of their correspondingeyelets or curved portions.

In embodiments in accordance herewith, the first, second and lateralsegments 240 a, 240 b, 240 c of the steering wire 240 may be formed by asingle wire. In other embodiments hereof, the first, second and/orlateral segments 240 a, 240 b, 240 c of the steering wire 240 may beformed by more than one wire joined together. In still otherembodiments, a first segment 240 a and a second segment 240 b of asteering wire 240 may be individual and separate wires and no lateralsegment may be disposed therebetween. Steering wires in accordance withembodiments hereof may be formed from one or more wires of a suitablestainless steel, Nitinol, UHMWPE (Ultra High Molecular WeightPolyethylene), and Nylon.

FIG. 2C depicts a cut away view of the handle component 104 showingproximal ends 244 a, 244 b of the steering wire 240 fixed within aninterior of the handle component 104 at locations 224 a, 224 b thereinsuch that proximalmost portions 246 a, 246 b of the first and secondsegments 240 a, 240 b of the steering wire 240 are disposed within theinterior of the handle component 104. In addition, the proximalmostportions 246 a, 246 b of the first and second segments 240 a, 240 b areoperably coupled to the rotatable knob 242 such that when the rotatableknob 242 is turned or rotated in a first direction the proximalmostportions 246 a, 246 b are wound or turned about a feature of the knob totransition the steering wire 240 into a taut configuration. When thesteering wire 240 is in a taut configuration, the first and secondsegments 240 a, 240 b are tensioned in a proximal direction, and whensufficient tensioning or force is applied to the sheath component 102via the interaction between the stops 246 of the steering wire 240 andthe eyelets/curved portions of the wire structure 212 deflection orbending of the distal portion 502 of the sheath component 102 willoccur.

In embodiments hereof, the amount of rotation of the knob 242 in thefirst direction may be selected depending on a desired degree ofdeflection Θ_(D), as determined by radiographic imaging or othersuitable imaging within the vasculature of the distal end 108 of thesheath component 102. In embodiments hereof, a degree of deflectionΘ_(D) is measured between the longitudinal axis L_(A) of the sheathcomponent 102 in a straightened, undeflected state, as shown in FIG. 1 ,and a central axis C_(A) of the deflected distal portion 502 of thesheath component 102, as shown in FIG. 5 . By way of example and notlimitation, a quarter turn of the knob 242 may correspond to anapproximately 15° deflection, a half turn of the knob 242 may correspondto an approximately 30° deflection and/or a three quarter turn of theknob 242 may correspond to an approximately 45° degree deflection. In anembodiment, the rotatable knob 242 may be provided with markings toindicate when the knob has been turned in the first direction to aposition that corresponds with the sheath component 102 being deflectedto a certain angle of deflection, such as by way of example and notlimitation, a series of markings with each marking corresponding to adeflection of the sheath component 102 to a respective one of 10°, 15°,20°, 25°, etc. In an embodiment, the rotatable knob 242 may also have alocked or delivery position at which the steering wire 240 issufficiently taut to prevent the radially-expandable portion 218 of thesheath component 102 from expanding and/or to aid in returning theradially-expandable portion 218 to an unexpanded state. In an embodimentin a locked position, the sheath component 102 may be fixed in adeflected state. In another embodiment, when the rotatable knob 242 isturned or rotated in a second direction (opposite of the firstdirection) the proximalmost portions 246 a, 246 b are unwound from aboutthe feature of the knob to transition the steering wire 240 into aslackened or loosened configuration. In an embodiment, the overalllength of the steering wire 240 is such that in the slackenedconfiguration the steering wire 240 permits a width of theradially-expandable portion 218 of the sheath component 102 to increaseor widen sufficiently to permit the passage of the valve prosthesisdelivery system 350 as described above.

In order to track one or more minimally invasive medical device to atreatment site within a patient, such as to track a valve prosthesisdelivery system to an incompetent heart valve of a patient, a clinicianmust first establish percutaneous access to a patient's vasculature. Ina method of providing percutaneous access to a patient's vasculature inaccordance herewith, which is presented by way of example, but notlimitation, a puncture needle (not shown) may be inserted through theskin and into a vessel, such as one of a femoral, brachial, or radialartery. The puncture needle may then be slightly withdrawn until a flashof blood appears and thereafter a guidewire (not shown) may be insertedthrough the puncture needle and advanced into the vessel. With theguidewire in place, the introducer apparatus 100 may be advanced overthe puncture needle such that the dilator 120 enlarges the access pointinto the vessel and the sheath component 102 of the introducer sheath110 gains access to the vessel. Thereafter, the dilator 120 is removed,and the sheath component 102 of the introducer sheath 110 is left behindin the vessel holding the tract open and protecting the vessel fromtrauma as one or more minimally invasive medical devices aresubsequently introduced into the vessel through.

In order to align the distal port 115 of the introducer sheath 110 withan ostium of a branch or side vessel, the rotatable knob 242 may berotated to sufficiently tension the steering wire 240 to bend the distalportion 502 of the sheath component 102 (as described above) to alignthe distal port 115 with the ostium.

While various embodiments have been described above, it should beunderstood that they have been presented only as illustrations andexamples of the present invention, and not by way of limitation. It willbe apparent to persons skilled in the relevant art that various changesin form and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment. All patents and publications discussed herein areincorporated by reference herein in their entirety.

What is claimed is:
 1. An introducer sheath for providing a prosthesisdelivery system percutaneous access to a patient's vasculature, thesheath comprising: a sheath component having a central lumen defined bya wall structure thereof, the wall structure formed from acircumferentially continuous inner layer with a radially-expandableportion, and a circumferentially discontinuous outermost layer that isconnected to the circumferentially continuous inner layer, thecircumferentially discontinuous outermost layer including first andsecond longitudinally-extending edges between which theradially-expandable portion of the inner layer is defined; and aC-shaped wire structure embedded within the circumferentiallydiscontinuous outermost layer of the wall structure for providing kinkresistance and reinforcement to the sheath component, wherein theradially-expandable portion of the circumferentially continuous innerlayer is disposed inwardly of the first and secondlongitudinally-extending edges of the circumferentially discontinuousoutermost layer in each of an unexpanded state of the sheath componentin which no portion of the sheath component is expanded and an expandedstate of the sheath component, and wherein in both the unexpanded stateand the expanded state of the sheath component the first and secondlongitudinally-extending edges of the circumferentially discontinuousoutermost layer are non-overlapping.
 2. The introducer sheath of claim1, wherein a first distance is defined between the first and secondlongitudinally-extending edges of the circumferentially discontinuousoutermost layer of the wall structure when the sheath component is inthe unexpanded state, and wherein a second distance, greater than thefirst distance, is defined between the first and secondlongitudinally-extending edges of the circumferentially discontinuousoutermost layer of the wall structure when the sheath component is inthe expanded state.
 3. The introducer sheath of claim 1, wherein theradially-expandable portion of the circumferentially continuous innerlayer of the wall structure has a first width when the sheath componentis in the unexpanded state, and wherein the radially-expandable portionof the circumferentially continuous inner layer of the wall structurehas a second width, greater than the first width, when the sheathcomponent is in the expanded state.
 4. The introducer sheath of claim 3,wherein the central lumen of the sheath component has a first diameterwhen the radially-expandable portion of the circumferentially continuousinner layer of the wall structure has the first width, and wherein thecentral lumen of the sheath component has a second diameter, greaterthan the first diameter, when the radially-expandable portion of thecircumferentially continuous inner layer of the wall structure has thesecond width.
 5. The introducer sheath of claim 4, wherein the centrallumen of the sheath component expands from the first diameter to thesecond diameter when at least a distal portion of the prosthesisdelivery system is passed therethrough.
 6. The introducer sheath ofclaim 1, wherein the C-shaped wire structure is formed from ashape-memory or resilient material to return the sheath component fromthe expanded state to the unexpanded state.
 7. An introducer sheath forproviding a prosthesis delivery system percutaneous access to apatient's vasculature comprising: a sheath component having a wallstructure formed from an inner liner with a radially-expandable portion,the radially-expandable portion having a first width when the sheathcomponent is in an unexpanded state and a second width, greater than thefirst width, when the sheath component is in an expanded state, whereinthe first width is a smallest width of the radially-expandable portion,and an outermost jacket that is connected to the inner liner, theoutermost jacket including first and second longitudinally-extendingedges between which the radially-expandable portion of the inner linerextends; and a C-shaped wire structure embedded within the outermostjacket of the wall structure for providing kink resistance andreinforcement to the sheath component, wherein the radially-expandableportion of the inner liner is disposed inwardly of the first and secondlongitudinally-extending edges of the outermost jacket in each of theunexpanded state and the expanded state of the sheath component; andwherein in both the unexpanded state and the expanded state of thesheath component the first and second longitudinally-extending edges ofthe outermost jacket are non-overlapping.
 8. The introducer sheath ofclaim 7, wherein a central lumen of the sheath component has a firstdiameter when the radially-expandable portion of the inner liner of thewall structure has the first width, and wherein the central lumen of thesheath component has a second diameter, greater than the first diameter,when the radially-expandable portion of the inner liner of the wallstructure has the second width.
 9. The introducer sheath of claim 8,wherein the central lumen of the sheath component expands from the firstdiameter to the second diameter when at least a distal portion of theprosthesis delivery system is passed therethrough.
 10. The introducersheath of claim 7, wherein a first distance is defined between the firstand second longitudinally-extending edges of the outermost jacket of thewall structure when the sheath component is in the unexpanded state, andwherein a second distance, greater than the first distance, is definedbetween the first and second longitudinally-extending edges of theoutermost jacket of the wall structure when the sheath component is inthe expanded state.
 11. The introducer sheath of claim 7, wherein theC-shaped wire structure is formed from a shape-memory or resilientmaterial to return the sheath component from the expanded state to theunexpanded state.
 12. The introducer sheath of claim 7, wherein theinner liner forms a circumferentially continuous inner layer.
 13. Theintroducer sheath of claim 12, wherein the outermost jacket forms acircumferentially discontinuous outermost layer.